<?php


namespace tools\office;

use ZipArchive;

class XLSXWriter
{
    //http://www.ecma-international.org/publications/standards/Ecma-376.htm
    //http://officeopenxml.com/SSstyles.php
    //------------------------------------------------------------------
    //http://office.microsoft.com/en-us/excel-help/excel-specifications-and-limits-HP010073849.aspx
    const EXCEL_2007_MAX_ROW=1048576;
    const EXCEL_2007_MAX_COL=16384;
    //------------------------------------------------------------------
    protected $title;
    protected $subject;
    protected $author;
    protected $company;
    protected $description;
    protected $keywords = array();

    protected $current_sheet;
    protected $sheets = array();
    protected $temp_files = array();
    protected $cell_styles = array();
    protected $number_formats = array();

    public function __construct()
    {
        if(!ini_get('date.timezone'))
        {
            //using date functions can kick out warning if this isn't set
            date_default_timezone_set('UTC');
        }
        $this->addCellStyle($number_format='GENERAL', $style_string=null);
        $this->addCellStyle($number_format='GENERAL', $style_string=null);
        $this->addCellStyle($number_format='GENERAL', $style_string=null);
        $this->addCellStyle($number_format='GENERAL', $style_string=null);
    }

    public function setTitle($title='') { $this->title=$title; }
    public function setSubject($subject='') { $this->subject=$subject; }
    public function setAuthor($author='') { $this->author=$author; }
    public function setCompany($company='') { $this->company=$company; }
    public function setKeywords($keywords='') { $this->keywords=$keywords; }
    public function setDescription($description='') { $this->description=$description; }
    public function setTempDir($tempdir='') { $this->tempdir=$tempdir; }

    public function __destruct()
    {
        if (!empty($this->temp_files)) {
            foreach($this->temp_files as $temp_file) {
                @unlink($temp_file);
            }
        }
    }

    protected function tempFilename()
    {
        $tempdir = !empty($this->tempdir) ? $this->tempdir : sys_get_temp_dir();
        $filename = tempnam($tempdir, "xlsx_writer_");
        $this->temp_files[] = $filename;
        return $filename;
    }

    public function writeToStdOut()
    {
        $temp_file = $this->tempFilename();
        self::writeToFile($temp_file);
        readfile($temp_file);
    }

    public function writeToString()
    {
        $temp_file = $this->tempFilename();
        self::writeToFile($temp_file);
        $string = file_get_contents($temp_file);
        return $string;
    }

    public function writeToFile($filename)
    {
        foreach($this->sheets as $sheet_name => $sheet) {
            self::finalizeSheet($sheet_name);//making sure all footers have been written
        }

        if ( file_exists( $filename ) ) {
            if ( is_writable( $filename ) ) {
                @unlink( $filename ); //if the zip already exists, remove it
            } else {
                self::log( "Error in " . __CLASS__ . "::" . __FUNCTION__ . ", file is not writeable." );
                return;
            }
        }
        $zip = new ZipArchive();
        if (empty($this->sheets))                       { self::log("Error in ".__CLASS__."::".__FUNCTION__.", no worksheets defined."); return; }
        if (!$zip->open($filename, ZipArchive::CREATE)) { self::log("Error in ".__CLASS__."::".__FUNCTION__.", unable to create zip."); return; }

        $zip->addEmptyDir("docProps/");
        $zip->addFromString("docProps/app.xml" , self::buildAppXML() );
        $zip->addFromString("docProps/core.xml", self::buildCoreXML());

        $zip->addEmptyDir("_rels/");
        $zip->addFromString("_rels/.rels", self::buildRelationshipsXML());

        $zip->addEmptyDir("xl/worksheets/");
        foreach($this->sheets as $sheet) {
            $zip->addFile($sheet->filename, "xl/worksheets/".$sheet->xmlname );
        }
        $zip->addFromString("xl/workbook.xml"         , self::buildWorkbookXML() );
        $zip->addFile($this->writeStylesXML(), "xl/styles.xml" );  //$zip->addFromString("xl/styles.xml"           , self::buildStylesXML() );
        $zip->addFromString("[Content_Types].xml"     , self::buildContentTypesXML() );

        $zip->addEmptyDir("xl/_rels/");
        $zip->addFromString("xl/_rels/workbook.xml.rels", self::buildWorkbookRelsXML() );
        $zip->close();
    }

    protected function initializeSheet($sheet_name, $col_widths=array(), $auto_filter=false, $freeze_rows=false, $freeze_columns=false )
    {
        //if already initialized
        if ($this->current_sheet==$sheet_name || isset($this->sheets[$sheet_name]))
            return;

        $sheet_filename = $this->tempFilename();
        $sheet_xmlname = 'sheet' . (count($this->sheets) + 1).".xml";
        $this->sheets[$sheet_name] = (object)array(
            'filename' => $sheet_filename,
            'sheetname' => $sheet_name,
            'xmlname' => $sheet_xmlname,
            'row_count' => 0,
            'file_writer' => new XLSXWriter_BuffererWriter($sheet_filename),
            'columns' => array(),
            'merge_cells' => array(),
            'max_cell_tag_start' => 0,
            'max_cell_tag_end' => 0,
            'auto_filter' => $auto_filter,
            'freeze_rows' => $freeze_rows,
            'freeze_columns' => $freeze_columns,
            'finalized' => false,
        );
        $sheet = &$this->sheets[$sheet_name];
        $tabselected = count($this->sheets) == 1 ? 'true' : 'false';//only first sheet is selected
        $max_cell= XLSXWriter::xlsCell(self::EXCEL_2007_MAX_ROW, self::EXCEL_2007_MAX_COL);//XFE1048577
        $sheet->file_writer->write('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n");
        $sheet->file_writer->write('<worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">');
        $sheet->file_writer->write(  '<sheetPr filterMode="false">');
        $sheet->file_writer->write(    '<pageSetUpPr fitToPage="false"/>');
        $sheet->file_writer->write(  '</sheetPr>');
        $sheet->max_cell_tag_start = $sheet->file_writer->ftell();
        $sheet->file_writer->write('<dimension ref="A1:' . $max_cell . '"/>');
        $sheet->max_cell_tag_end = $sheet->file_writer->ftell();
        $sheet->file_writer->write(  '<sheetViews>');
        $sheet->file_writer->write(    '<sheetView colorId="64" defaultGridColor="true" rightToLeft="false" showFormulas="false" showGridLines="true" showOutlineSymbols="true" showRowColHeaders="true" showZeros="true" tabSelected="' . $tabselected . '" topLeftCell="A1" view="normal" windowProtection="false" workbookViewId="0" zoomScale="100" zoomScaleNormal="100" zoomScalePageLayoutView="100">');
        if ($sheet->freeze_rows && $sheet->freeze_columns) {
            $sheet->file_writer->write(      '<pane ySplit="'.$sheet->freeze_rows.'" xSplit="'.$sheet->freeze_columns.'" topLeftCell="'.self::xlsCell($sheet->freeze_rows, $sheet->freeze_columns).'" activePane="bottomRight" state="frozen"/>');
            $sheet->file_writer->write(      '<selection activeCell="'.self::xlsCell($sheet->freeze_rows, 0).'" activeCellId="0" pane="topRight" sqref="'.self::xlsCell($sheet->freeze_rows, 0).'"/>');
            $sheet->file_writer->write(      '<selection activeCell="'.self::xlsCell(0, $sheet->freeze_columns).'" activeCellId="0" pane="bottomLeft" sqref="'.self::xlsCell(0, $sheet->freeze_columns).'"/>');
            $sheet->file_writer->write(      '<selection activeCell="'.self::xlsCell($sheet->freeze_rows, $sheet->freeze_columns).'" activeCellId="0" pane="bottomRight" sqref="'.self::xlsCell($sheet->freeze_rows, $sheet->freeze_columns).'"/>');
        }
        elseif ($sheet->freeze_rows) {
            $sheet->file_writer->write(      '<pane ySplit="'.$sheet->freeze_rows.'" topLeftCell="'.self::xlsCell($sheet->freeze_rows, 0).'" activePane="bottomLeft" state="frozen"/>');
            $sheet->file_writer->write(      '<selection activeCell="'.self::xlsCell($sheet->freeze_rows, 0).'" activeCellId="0" pane="bottomLeft" sqref="'.self::xlsCell($sheet->freeze_rows, 0).'"/>');
        }
        elseif ($sheet->freeze_columns) {
            $sheet->file_writer->write(      '<pane xSplit="'.$sheet->freeze_columns.'" topLeftCell="'.self::xlsCell(0, $sheet->freeze_columns).'" activePane="topRight" state="frozen"/>');
            $sheet->file_writer->write(      '<selection activeCell="'.self::xlsCell(0, $sheet->freeze_columns).'" activeCellId="0" pane="topRight" sqref="'.self::xlsCell(0, $sheet->freeze_columns).'"/>');
        }
        else { // not frozen
            $sheet->file_writer->write(      '<selection activeCell="A1" activeCellId="0" pane="topLeft" sqref="A1"/>');
        }
        $sheet->file_writer->write(    '</sheetView>');
        $sheet->file_writer->write(  '</sheetViews>');
        $sheet->file_writer->write(  '<cols>');
        $i=0;
        if (!empty($col_widths)) {
            foreach($col_widths as $column_width) {
                $sheet->file_writer->write(  '<col collapsed="false" hidden="false" max="'.($i+1).'" min="'.($i+1).'" style="0" customWidth="true" width="'.floatval($column_width).'"/>');
                $i++;
            }
        }
        $sheet->file_writer->write(  '<col collapsed="false" hidden="false" max="1024" min="'.($i+1).'" style="0" customWidth="false" width="11.5"/>');
        $sheet->file_writer->write(  '</cols>');
        $sheet->file_writer->write(  '<sheetData>');
    }

    private function addCellStyle($number_format, $cell_style_string)
    {
        $number_format_idx = self::add_to_list_get_index($this->number_formats, $number_format);
        $lookup_string = $number_format_idx.";".$cell_style_string;
        $cell_style_idx = self::add_to_list_get_index($this->cell_styles, $lookup_string);
        return $cell_style_idx;
    }

    private function initializeColumnTypes($header_types)
    {
        $column_types = array();
        foreach($header_types as $v)
        {
            $number_format = self::numberFormatStandardized($v);
            $number_format_type = self::determineNumberFormatType($number_format);
            $cell_style_idx = $this->addCellStyle($number_format, $style_string=null);
            $column_types[] = array('number_format' => $number_format,//contains excel format like 'YYYY-MM-DD HH:MM:SS'
                'number_format_type' => $number_format_type, //contains friendly format like 'datetime'
                'default_cell_style' => $cell_style_idx,
            );
        }
        return $column_types;
    }

    public function writeSheetHeader($sheet_name, array $header_types, $col_options = null)
    {
        if (empty($sheet_name) || empty($header_types) || !empty($this->sheets[$sheet_name]))
            return;

        $suppress_row = isset($col_options['suppress_row']) ? intval($col_options['suppress_row']) : false;
        if (is_bool($col_options))
        {
            self::log( "Warning! passing $suppress_row=false|true to writeSheetHeader() is deprecated, this will be removed in a future version." );
            $suppress_row = intval($col_options);
        }
        $style = &$col_options;

        $col_widths = isset($col_options['widths']) ? (array)$col_options['widths'] : array();
        $auto_filter = isset($col_options['auto_filter']) ? intval($col_options['auto_filter']) : false;
        $freeze_rows = isset($col_options['freeze_rows']) ? intval($col_options['freeze_rows']) : false;
        $freeze_columns = isset($col_options['freeze_columns']) ? intval($col_options['freeze_columns']) : false;
        self::initializeSheet($sheet_name, $col_widths, $auto_filter, $freeze_rows, $freeze_columns);
        $sheet = &$this->sheets[$sheet_name];
        $sheet->columns = $this->initializeColumnTypes($header_types);
        if (!$suppress_row)
        {
            $header_row = array_keys($header_types);

            $sheet->file_writer->write('<row collapsed="false" customFormat="false" customHeight="false" hidden="false" ht="12.1" outlineLevel="0" r="' . (1) . '">');
            foreach ($header_row as $c => $v) {
                $cell_style_idx = empty($style) ? $sheet->columns[$c]['default_cell_style'] : $this->addCellStyle( 'GENERAL', json_encode(isset($style[0]) ? $style[$c] : $style) );
                $this->writeCell($sheet->file_writer, 0, $c, $v, $number_format_type='n_string', $cell_style_idx);
            }
            $sheet->file_writer->write('</row>');
            $sheet->row_count++;
        }
        $this->current_sheet = $sheet_name;
    }

    public function writeSheetRow($sheet_name, array $row, $row_options=null)
    {
        if (empty($sheet_name))
            return;

        self::initializeSheet($sheet_name);
        $sheet = &$this->sheets[$sheet_name];
        if (count($sheet->columns) < count($row)) {
            $default_column_types = $this->initializeColumnTypes( array_fill($from=0, $until=count($row), 'GENERAL') );//will map to n_auto
            $sheet->columns = array_merge((array)$sheet->columns, $default_column_types);
        }

        if (!empty($row_options))
        {
            $ht = isset($row_options['height']) ? floatval($row_options['height']) : 12.1;
            $customHt = isset($row_options['height']) ? true : false;
            $hidden = isset($row_options['hidden']) ? (bool)($row_options['hidden']) : false;
            $collapsed = isset($row_options['collapsed']) ? (bool)($row_options['collapsed']) : false;
            $sheet->file_writer->write('<row collapsed="'.($collapsed).'" customFormat="false" customHeight="'.($customHt).'" hidden="'.($hidden).'" ht="'.($ht).'" outlineLevel="0" r="' . ($sheet->row_count + 1) . '">');
        }
        else
        {
            $sheet->file_writer->write('<row collapsed="false" customFormat="false" customHeight="false" hidden="false" ht="12.1" outlineLevel="0" r="' . ($sheet->row_count + 1) . '">');
        }

        $style = &$row_options;
        $c=0;
        foreach ($row as $v) {
            $number_format = $sheet->columns[$c]['number_format'];
            $number_format_type = $sheet->columns[$c]['number_format_type'];
            $cell_style_idx = empty($style) ? $sheet->columns[$c]['default_cell_style'] : $this->addCellStyle( $number_format, json_encode(isset($style[0]) ? $style[$c] : $style) );
            $this->writeCell($sheet->file_writer, $sheet->row_count, $c, $v, $number_format_type, $cell_style_idx);
            $c++;
        }
        $sheet->file_writer->write('</row>');
        $sheet->row_count++;
        $this->current_sheet = $sheet_name;
    }

    public function countSheetRows($sheet_name = '')
    {
        $sheet_name = $sheet_name ?: $this->current_sheet;
        return array_key_exists($sheet_name, $this->sheets) ? $this->sheets[$sheet_name]->row_count : 0;
    }

    protected function finalizeSheet($sheet_name)
    {
        if (empty($sheet_name) || $this->sheets[$sheet_name]->finalized)
            return;

        $sheet = &$this->sheets[$sheet_name];

        $sheet->file_writer->write(    '</sheetData>');

        if (!empty($sheet->merge_cells)) {
            $sheet->file_writer->write(    '<mergeCells>');
            foreach ($sheet->merge_cells as $range) {
                $sheet->file_writer->write(        '<mergeCell ref="' . $range . '"/>');
            }
            $sheet->file_writer->write(    '</mergeCells>');
        }

        $max_cell = self::xlsCell($sheet->row_count - 1, count($sheet->columns) - 1);

        if ($sheet->auto_filter) {
            $sheet->file_writer->write(    '<autoFilter ref="A1:' . $max_cell . '"/>');
        }

        $sheet->file_writer->write(    '<printOptions headings="false" gridLines="false" gridLinesSet="true" horizontalCentered="false" verticalCentered="false"/>');
        $sheet->file_writer->write(    '<pageMargins left="0.5" right="0.5" top="1.0" bottom="1.0" header="0.5" footer="0.5"/>');
        $sheet->file_writer->write(    '<pageSetup blackAndWhite="false" cellComments="none" copies="1" draft="false" firstPageNumber="1" fitToHeight="1" fitToWidth="1" horizontalDpi="300" orientation="portrait" pageOrder="downThenOver" paperSize="1" scale="100" useFirstPageNumber="true" usePrinterDefaults="false" verticalDpi="300"/>');
        $sheet->file_writer->write(    '<headerFooter differentFirst="false" differentOddEven="false">');
        $sheet->file_writer->write(        '<oddHeader>&amp;C&amp;&quot;Times New Roman,Regular&quot;&amp;12&amp;A</oddHeader>');
        $sheet->file_writer->write(        '<oddFooter>&amp;C&amp;&quot;Times New Roman,Regular&quot;&amp;12Page &amp;P</oddFooter>');
        $sheet->file_writer->write(    '</headerFooter>');
        $sheet->file_writer->write('</worksheet>');

        $max_cell_tag = '<dimension ref="A1:' . $max_cell . '"/>';
        $padding_length = $sheet->max_cell_tag_end - $sheet->max_cell_tag_start - strlen($max_cell_tag);
        $sheet->file_writer->fseek($sheet->max_cell_tag_start);
        $sheet->file_writer->write($max_cell_tag.str_repeat(" ", $padding_length));
        $sheet->file_writer->close();
        $sheet->finalized=true;
    }

    public function markMergedCell($sheet_name, $start_cell_row, $start_cell_column, $end_cell_row, $end_cell_column)
    {
        if (empty($sheet_name) || $this->sheets[$sheet_name]->finalized)
            return;

        self::initializeSheet($sheet_name);
        $sheet = &$this->sheets[$sheet_name];

        $startCell = self::xlsCell($start_cell_row, $start_cell_column);
        $endCell = self::xlsCell($end_cell_row, $end_cell_column);
        $sheet->merge_cells[] = $startCell . ":" . $endCell;
    }

    public function writeSheet(array $data, $sheet_name='', array $header_types=array())
    {
        $sheet_name = empty($sheet_name) ? 'Sheet1' : $sheet_name;
        $data = empty($data) ? array(array('')) : $data;
        if (!empty($header_types))
        {
            $this->writeSheetHeader($sheet_name, $header_types);
        }
        foreach($data as $i=>$row)
        {
            $this->writeSheetRow($sheet_name, $row);
        }
        $this->finalizeSheet($sheet_name);
    }

    protected function writeCell(XLSXWriter_BuffererWriter &$file, $row_number, $column_number, $value, $num_format_type, $cell_style_idx)
    {
        $cell_name = self::xlsCell($row_number, $column_number);

        if (!is_scalar($value) || $value==='') { //objects, array, empty
            $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'"/>');
        } elseif (is_string($value) && $value{0}=='='){
            $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="s"><f>'.self::xmlspecialchars($value).'</f></c>');
        } elseif ($num_format_type=='n_date') {
            $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="n"><v>'.intval(self::convert_date_time($value)).'</v></c>');
        } elseif ($num_format_type=='n_datetime') {
            $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="n"><v>'.self::convert_date_time($value).'</v></c>');
        } elseif ($num_format_type=='n_numeric') {
            $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="n"><v>'.self::xmlspecialchars($value).'</v></c>');//int,float,currency
        } elseif ($num_format_type=='n_string') {
            $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="inlineStr"><is><t>'.self::xmlspecialchars($value).'</t></is></c>');
        } elseif ($num_format_type=='n_auto' || 1) { //auto-detect unknown column types
            if (!is_string($value) || $value=='0' || ($value[0]!='0' && ctype_digit($value)) || preg_match("/^\-?(0|[1-9][0-9]*)(\.[0-9]+)?$/", $value)){
                $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="n"><v>'.self::xmlspecialchars($value).'</v></c>');//int,float,currency
            } else { //implied: ($cell_format=='string')
                $file->write('<c r="'.$cell_name.'" s="'.$cell_style_idx.'" t="inlineStr"><is><t>'.self::xmlspecialchars($value).'</t></is></c>');
            }
        }
    }

    protected function styleFontIndexes()
    {
        static $border_allowed = array('left','right','top','bottom');
        static $border_style_allowed = array('thin','medium','thick','dashDot','dashDotDot','dashed','dotted','double','hair','mediumDashDot','mediumDashDotDot','mediumDashed','slantDashDot');
        static $horizontal_allowed = array('general','left','right','justify','center');
        static $vertical_allowed = array('bottom','center','distributed','top');
        $default_font = array('size'=>'10','name'=>'Arial','family'=>'2');
        $fills = array('','');//2 placeholders for static xml later
        $fonts = array('','','','');//4 placeholders for static xml later
        $borders = array('');//1 placeholder for static xml later
        $style_indexes = array();
        foreach($this->cell_styles as $i=>$cell_style_string)
        {
            $semi_colon_pos = strpos($cell_style_string,";");
            $number_format_idx = substr($cell_style_string, 0, $semi_colon_pos);
            $style_json_string = substr($cell_style_string, $semi_colon_pos+1);
            $style = @json_decode($style_json_string, $as_assoc=true);

            $style_indexes[$i] = array('num_fmt_idx'=>$number_format_idx);//initialize entry
            if (isset($style['border']) && is_string($style['border']))//border is a comma delimited str
            {
                $border_value['side'] = array_intersect(explode(",", $style['border']), $border_allowed);
                if (isset($style['border-style']) && in_array($style['border-style'],$border_style_allowed))
                {
                    $border_value['style'] = $style['border-style'];
                }
                if (isset($style['border-color']) && is_string($style['border-color']) && $style['border-color'][0]=='#')
                {
                    $v = substr($style['border-color'],1,6);
                    $v = strlen($v)==3 ? $v[0].$v[0].$v[1].$v[1].$v[2].$v[2] : $v;// expand cf0 => ccff00
                    $border_value['color'] = "FF".strtoupper($v);
                }
                $style_indexes[$i]['border_idx'] = self::add_to_list_get_index($borders, json_encode($border_value));
            }
            if (isset($style['fill']) && is_string($style['fill']) && $style['fill'][0]=='#')
            {
                $v = substr($style['fill'],1,6);
                $v = strlen($v)==3 ? $v[0].$v[0].$v[1].$v[1].$v[2].$v[2] : $v;// expand cf0 => ccff00
                $style_indexes[$i]['fill_idx'] = self::add_to_list_get_index($fills, "FF".strtoupper($v) );
            }
            if (isset($style['halign']) && in_array($style['halign'],$horizontal_allowed))
            {
                $style_indexes[$i]['alignment'] = true;
                $style_indexes[$i]['halign'] = $style['halign'];
            }
            if (isset($style['valign']) && in_array($style['valign'],$vertical_allowed))
            {
                $style_indexes[$i]['alignment'] = true;
                $style_indexes[$i]['valign'] = $style['valign'];
            }
            if (isset($style['wrap_text']))
            {
                $style_indexes[$i]['alignment'] = true;
                $style_indexes[$i]['wrap_text'] = (bool)$style['wrap_text'];
            }

            $font = $default_font;
            if (isset($style['font-size']))
            {
                $font['size'] = floatval($style['font-size']);//floatval to allow "10.5" etc
            }
            if (isset($style['font']) && is_string($style['font']))
            {
                if ($style['font']=='Comic Sans MS') { $font['family']=4; }
                if ($style['font']=='Times New Roman') { $font['family']=1; }
                if ($style['font']=='Courier New') { $font['family']=3; }
                $font['name'] = strval($style['font']);
            }
            if (isset($style['font-style']) && is_string($style['font-style']))
            {
                if (strpos($style['font-style'], 'bold')!==false) { $font['bold'] = true; }
                if (strpos($style['font-style'], 'italic')!==false) { $font['italic'] = true; }
                if (strpos($style['font-style'], 'strike')!==false) { $font['strike'] = true; }
                if (strpos($style['font-style'], 'underline')!==false) { $font['underline'] = true; }
            }
            if (isset($style['color']) && is_string($style['color']) && $style['color'][0]=='#' )
            {
                $v = substr($style['color'],1,6);
                $v = strlen($v)==3 ? $v[0].$v[0].$v[1].$v[1].$v[2].$v[2] : $v;// expand cf0 => ccff00
                $font['color'] = "FF".strtoupper($v);
            }
            if ($font!=$default_font)
            {
                $style_indexes[$i]['font_idx'] = self::add_to_list_get_index($fonts, json_encode($font) );
            }
        }
        return array('fills'=>$fills,'fonts'=>$fonts,'borders'=>$borders,'styles'=>$style_indexes );
    }

    protected function writeStylesXML()
    {
        $r = self::styleFontIndexes();
        $fills = $r['fills'];
        $fonts = $r['fonts'];
        $borders = $r['borders'];
        $style_indexes = $r['styles'];

        $temporary_filename = $this->tempFilename();
        $file = new XLSXWriter_BuffererWriter($temporary_filename);
        $file->write('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'."\n");
        $file->write('<styleSheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">');
        $file->write('<numFmts count="'.count($this->number_formats).'">');
        foreach($this->number_formats as $i=>$v) {
            $file->write('<numFmt numFmtId="'.(164+$i).'" formatCode="'.self::xmlspecialchars($v).'" />');
        }
        //$file->write(		'<numFmt formatCode="GENERAL" numFmtId="164"/>');
        //$file->write(		'<numFmt formatCode="[$$-1009]#,##0.00;[RED]\-[$$-1009]#,##0.00" numFmtId="165"/>');
        //$file->write(		'<numFmt formatCode="YYYY-MM-DD\ HH:MM:SS" numFmtId="166"/>');
        //$file->write(		'<numFmt formatCode="YYYY-MM-DD" numFmtId="167"/>');
        $file->write('</numFmts>');

        $file->write('<fonts count="'.(count($fonts)).'">');
        $file->write(		'<font><name val="Arial"/><charset val="1"/><family val="2"/><sz val="10"/></font>');
        $file->write(		'<font><name val="Arial"/><family val="0"/><sz val="10"/></font>');
        $file->write(		'<font><name val="Arial"/><family val="0"/><sz val="10"/></font>');
        $file->write(		'<font><name val="Arial"/><family val="0"/><sz val="10"/></font>');

        foreach($fonts as $font) {
            if (!empty($font)) { //fonts have 4 empty placeholders in array to offset the 4 static xml entries above
                $f = json_decode($font,true);
                $file->write('<font>');
                $file->write(	'<name val="'.htmlspecialchars($f['name']).'"/><charset val="1"/><family val="'.intval($f['family']).'"/>');
                $file->write(	'<sz val="'.intval($f['size']).'"/>');
                if (!empty($f['color'])) { $file->write('<color rgb="'.strval($f['color']).'"/>'); }
                if (!empty($f['bold'])) { $file->write('<b val="true"/>'); }
                if (!empty($f['italic'])) { $file->write('<i val="true"/>'); }
                if (!empty($f['underline'])) { $file->write('<u val="single"/>'); }
                if (!empty($f['strike'])) { $file->write('<strike val="true"/>'); }
                $file->write('</font>');
            }
        }
        $file->write('</fonts>');

        $file->write('<fills count="'.(count($fills)).'">');
        $file->write(	'<fill><patternFill patternType="none"/></fill>');
        $file->write(	'<fill><patternFill patternType="gray125"/></fill>');
        foreach($fills as $fill) {
            if (!empty($fill)) { //fills have 2 empty placeholders in array to offset the 2 static xml entries above
                $file->write('<fill><patternFill patternType="solid"><fgColor rgb="'.strval($fill).'"/><bgColor indexed="64"/></patternFill></fill>');
            }
        }
        $file->write('</fills>');

        $file->write('<borders count="'.(count($borders)).'">');
        $file->write(    '<border diagonalDown="false" diagonalUp="false"><left/><right/><top/><bottom/><diagonal/></border>');
        foreach($borders as $border) {
            if (!empty($border)) { //fonts have an empty placeholder in the array to offset the static xml entry above
                $pieces = json_decode($border,true);
                $border_style = !empty($pieces['style']) ? $pieces['style'] : 'hair';
                $border_color = !empty($pieces['color']) ? '<color rgb="'.strval($pieces['color']).'"/>' : '';
                $file->write('<border diagonalDown="false" diagonalUp="false">');
                foreach (array('left', 'right', 'top', 'bottom') as $side)
                {
                    $show_side = in_array($side,$pieces['side']) ? true : false;
                    $file->write($show_side ? "<$side style=\"$border_style\">$border_color</$side>" : "<$side/>");
                }
                $file->write(  '<diagonal/>');
                $file->write('</border>');
            }
        }
        $file->write('</borders>');

        $file->write('<cellStyleXfs count="20">');
        $file->write(		'<xf applyAlignment="true" applyBorder="true" applyFont="true" applyProtection="true" borderId="0" fillId="0" fontId="0" numFmtId="164">');
        $file->write(		'<alignment horizontal="general" indent="0" shrinkToFit="false" textRotation="0" vertical="bottom" wrapText="false"/>');
        $file->write(		'<protection hidden="false" locked="true"/>');
        $file->write(		'</xf>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="2" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="2" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="43"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="41"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="44"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="42"/>');
        $file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="9"/>');
        $file->write('</cellStyleXfs>');

        $file->write('<cellXfs count="'.(count($style_indexes)).'">');
        //$file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="164" xfId="0"/>');
        //$file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="165" xfId="0"/>');
        //$file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="166" xfId="0"/>');
        //$file->write(		'<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="167" xfId="0"/>');
        foreach($style_indexes as $v)
        {
            $applyAlignment = isset($v['alignment']) ? 'true' : 'false';
            $wrapText = !empty($v['wrap_text']) ? 'true' : 'false';
            $horizAlignment = isset($v['halign']) ? $v['halign'] : 'general';
            $vertAlignment = isset($v['valign']) ? $v['valign'] : 'bottom';
            $applyBorder = isset($v['border_idx']) ? 'true' : 'false';
            $applyFont = 'true';
            $borderIdx = isset($v['border_idx']) ? intval($v['border_idx']) : 0;
            $fillIdx = isset($v['fill_idx']) ? intval($v['fill_idx']) : 0;
            $fontIdx = isset($v['font_idx']) ? intval($v['font_idx']) : 0;
            //$file->write('<xf applyAlignment="'.$applyAlignment.'" applyBorder="'.$applyBorder.'" applyFont="'.$applyFont.'" applyProtection="false" borderId="'.($borderIdx).'" fillId="'.($fillIdx).'" fontId="'.($fontIdx).'" numFmtId="'.(164+$v['num_fmt_idx']).'" xfId="0"/>');
            $file->write('<xf applyAlignment="'.$applyAlignment.'" applyBorder="'.$applyBorder.'" applyFont="'.$applyFont.'" applyProtection="false" borderId="'.($borderIdx).'" fillId="'.($fillIdx).'" fontId="'.($fontIdx).'" numFmtId="'.(164+$v['num_fmt_idx']).'" xfId="0">');
            $file->write('	<alignment horizontal="'.$horizAlignment.'" vertical="'.$vertAlignment.'" textRotation="0" wrapText="'.$wrapText.'" indent="0" shrinkToFit="false"/>');
            $file->write('	<protection locked="true" hidden="false"/>');
            $file->write('</xf>');
        }
        $file->write('</cellXfs>');
        $file->write(	'<cellStyles count="6">');
        $file->write(		'<cellStyle builtinId="0" customBuiltin="false" name="Normal" xfId="0"/>');
        $file->write(		'<cellStyle builtinId="3" customBuiltin="false" name="Comma" xfId="15"/>');
        $file->write(		'<cellStyle builtinId="6" customBuiltin="false" name="Comma [0]" xfId="16"/>');
        $file->write(		'<cellStyle builtinId="4" customBuiltin="false" name="Currency" xfId="17"/>');
        $file->write(		'<cellStyle builtinId="7" customBuiltin="false" name="Currency [0]" xfId="18"/>');
        $file->write(		'<cellStyle builtinId="5" customBuiltin="false" name="Percent" xfId="19"/>');
        $file->write(	'</cellStyles>');
        $file->write('</styleSheet>');
        $file->close();
        return $temporary_filename;
    }

    protected function buildAppXML()
    {
        $app_xml="";
        $app_xml.='<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'."\n";
        $app_xml.='<Properties xmlns="http://schemas.openxmlformats.org/officeDocument/2006/extended-properties" xmlns:vt="http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes">';
        $app_xml.='<TotalTime>0</TotalTime>';
        $app_xml.='<Company>'.self::xmlspecialchars($this->company).'</Company>';
        $app_xml.='</Properties>';
        return $app_xml;
    }

    protected function buildCoreXML()
    {
        $core_xml="";
        $core_xml.='<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'."\n";
        $core_xml.='<cp:coreProperties xmlns:cp="http://schemas.openxmlformats.org/package/2006/metadata/core-properties" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcmitype="http://purl.org/dc/dcmitype/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">';
        $core_xml.='<dcterms:created xsi:type="dcterms:W3CDTF">'.date("Y-m-d\TH:i:s.00\Z").'</dcterms:created>';//$date_time = '2014-10-25T15:54:37.00Z';
        $core_xml.='<dc:title>'.self::xmlspecialchars($this->title).'</dc:title>';
        $core_xml.='<dc:subject>'.self::xmlspecialchars($this->subject).'</dc:subject>';
        $core_xml.='<dc:creator>'.self::xmlspecialchars($this->author).'</dc:creator>';
        if (!empty($this->keywords)) {
            $core_xml.='<cp:keywords>'.self::xmlspecialchars(implode (", ", (array)$this->keywords)).'</cp:keywords>';
        }
        $core_xml.='<dc:description>'.self::xmlspecialchars($this->description).'</dc:description>';
        $core_xml.='<cp:revision>0</cp:revision>';
        $core_xml.='</cp:coreProperties>';
        return $core_xml;
    }

    protected function buildRelationshipsXML()
    {
        $rels_xml="";
        $rels_xml.='<?xml version="1.0" encoding="UTF-8"?>'."\n";
        $rels_xml.='<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">';
        $rels_xml.='<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/>';
        $rels_xml.='<Relationship Id="rId2" Type="http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties" Target="docProps/core.xml"/>';
        $rels_xml.='<Relationship Id="rId3" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/extended-properties" Target="docProps/app.xml"/>';
        $rels_xml.="\n";
        $rels_xml.='</Relationships>';
        return $rels_xml;
    }

    protected function buildWorkbookXML()
    {
        $i=0;
        $workbook_xml="";
        $workbook_xml.='<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'."\n";
        $workbook_xml.='<workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">';
        $workbook_xml.='<fileVersion appName="Calc"/><workbookPr backupFile="false" showObjects="all" date1904="false"/><workbookProtection/>';
        $workbook_xml.='<bookViews><workbookView activeTab="0" firstSheet="0" showHorizontalScroll="true" showSheetTabs="true" showVerticalScroll="true" tabRatio="212" windowHeight="8192" windowWidth="16384" xWindow="0" yWindow="0"/></bookViews>';
        $workbook_xml.='<sheets>';
        foreach($this->sheets as $sheet_name=>$sheet) {
            $sheetname = self::sanitize_sheetname($sheet->sheetname);
            $workbook_xml.='<sheet name="'.self::xmlspecialchars($sheetname).'" sheetId="'.($i+1).'" state="visible" r:id="rId'.($i+2).'"/>';
            $i++;
        }
        $workbook_xml.='</sheets>';
        $workbook_xml.='<definedNames>';
        foreach($this->sheets as $sheet_name=>$sheet) {
            if ($sheet->auto_filter) {
                $sheetname = self::sanitize_sheetname($sheet->sheetname);
                $workbook_xml.='<definedName name="_xlnm._FilterDatabase" localSheetId="0" hidden="1">\''.self::xmlspecialchars($sheetname).'\'!$A$1:' . self::xlsCell($sheet->row_count - 1, count($sheet->columns) - 1, true) . '</definedName>';
                $i++;
            }
        }
        $workbook_xml.='</definedNames>';
        $workbook_xml.='<calcPr iterateCount="100" refMode="A1" iterate="false" iterateDelta="0.001"/></workbook>';
        return $workbook_xml;
    }

    protected function buildWorkbookRelsXML()
    {
        $i=0;
        $wkbkrels_xml="";
        $wkbkrels_xml.='<?xml version="1.0" encoding="UTF-8"?>'."\n";
        $wkbkrels_xml.='<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">';
        $wkbkrels_xml.='<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/>';
        foreach($this->sheets as $sheet_name=>$sheet) {
            $wkbkrels_xml.='<Relationship Id="rId'.($i+2).'" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/'.($sheet->xmlname).'"/>';
            $i++;
        }
        $wkbkrels_xml.="\n";
        $wkbkrels_xml.='</Relationships>';
        return $wkbkrels_xml;
    }

    protected function buildContentTypesXML()
    {
        $content_types_xml="";
        $content_types_xml.='<?xml version="1.0" encoding="UTF-8"?>'."\n";
        $content_types_xml.='<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">';
        $content_types_xml.='<Override PartName="/_rels/.rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>';
        $content_types_xml.='<Override PartName="/xl/_rels/workbook.xml.rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>';
        foreach($this->sheets as $sheet_name=>$sheet) {
            $content_types_xml.='<Override PartName="/xl/worksheets/'.($sheet->xmlname).'" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml"/>';
        }
        $content_types_xml.='<Override PartName="/xl/workbook.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml"/>';
        $content_types_xml.='<Override PartName="/xl/styles.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml"/>';
        $content_types_xml.='<Override PartName="/docProps/app.xml" ContentType="application/vnd.openxmlformats-officedocument.extended-properties+xml"/>';
        $content_types_xml.='<Override PartName="/docProps/core.xml" ContentType="application/vnd.openxmlformats-package.core-properties+xml"/>';
        $content_types_xml.="\n";
        $content_types_xml.='</Types>';
        return $content_types_xml;
    }

    //------------------------------------------------------------------
    /*
     * @param $row_number int, zero based
     * @param $column_number int, zero based
     * @param $absolute bool
     * @return Cell label/coordinates, ex: A1, C3, AA42 (or if $absolute==true: $A$1, $C$3, $AA$42)
     * */
    public static function xlsCell($row_number, $column_number, $absolute=false)
    {
        $n = $column_number;
        for($r = ""; $n >= 0; $n = intval($n / 26) - 1) {
            $r = chr($n%26 + 0x41) . $r;
        }
        if ($absolute) {
            return '$' . $r . '$' . ($row_number+1);
        }
        return $r . ($row_number+1);
    }
    //------------------------------------------------------------------
    public static function log($string)
    {
        file_put_contents("php://stderr", date("Y-m-d H:i:s:").rtrim(is_array($string) ? json_encode($string) : $string)."\n");
    }
    //------------------------------------------------------------------
    public static function sanitize_filename($filename) //http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx
    {
        $nonprinting = array_map('chr', range(0,31));
        $invalid_chars = array('<', '>', '?', '"', ':', '|', '\\', '/', '*', '&');
        $all_invalids = array_merge($nonprinting,$invalid_chars);
        return str_replace($all_invalids, "", $filename);
    }
    //------------------------------------------------------------------
    public static function sanitize_sheetname($sheetname)
    {
        static $badchars  = '\\/?*:[]';
        static $goodchars = '        ';
        $sheetname = strtr($sheetname, $badchars, $goodchars);
        $sheetname = mb_substr($sheetname, 0, 31);
        $sheetname = trim(trim(trim($sheetname),"'"));//trim before and after trimming single quotes
        return !empty($sheetname) ? $sheetname : 'Sheet'.((rand()%900)+100);
    }
    //------------------------------------------------------------------
    public static function xmlspecialchars($val)
    {
        //note, badchars does not include \t\n\r (\x09\x0a\x0d)
        static $badchars = "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x0b\x0c\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x7f";
        static $goodchars = "                              ";
        return strtr(htmlspecialchars($val, ENT_QUOTES | ENT_XML1), $badchars, $goodchars);//strtr appears to be faster than str_replace
    }
    //------------------------------------------------------------------
    public static function array_first_key(array $arr)
    {
        reset($arr);
        $first_key = key($arr);
        return $first_key;
    }
    //------------------------------------------------------------------
    private static function determineNumberFormatType($num_format)
    {
        $num_format = preg_replace("/\[(Black|Blue|Cyan|Green|Magenta|Red|White|Yellow)\]/i", "", $num_format);
        if ($num_format=='GENERAL') return 'n_auto';
        if ($num_format=='@') return 'n_string';
        if ($num_format=='0') return 'n_numeric';
        if (preg_match('/[H]{1,2}:[M]{1,2}(?![^"]*+")/i', $num_format)) return 'n_datetime';
        if (preg_match('/[M]{1,2}:[S]{1,2}(?![^"]*+")/i', $num_format)) return 'n_datetime';
        if (preg_match('/[Y]{2,4}(?![^"]*+")/i', $num_format)) return 'n_date';
        if (preg_match('/[D]{1,2}(?![^"]*+")/i', $num_format)) return 'n_date';
        if (preg_match('/[M]{1,2}(?![^"]*+")/i', $num_format)) return 'n_date';
        if (preg_match('/$(?![^"]*+")/', $num_format)) return 'n_numeric';
        if (preg_match('/%(?![^"]*+")/', $num_format)) return 'n_numeric';
        if (preg_match('/0(?![^"]*+")/', $num_format)) return 'n_numeric';
        return 'n_auto';
    }
    //------------------------------------------------------------------
    private static function numberFormatStandardized($num_format)
    {
        if ($num_format=='money') { $num_format='dollar'; }
        if ($num_format=='number') { $num_format='integer'; }

        if      ($num_format=='string')   $num_format='@';
        else if ($num_format=='integer')  $num_format='0';
        else if ($num_format=='date')     $num_format='YYYY-MM-DD';
        else if ($num_format=='datetime') $num_format='YYYY-MM-DD HH:MM:SS';
        else if ($num_format=='price')    $num_format='#,##0.00';
        else if ($num_format=='dollar')   $num_format='[$$-1009]#,##0.00;[RED]-[$$-1009]#,##0.00';
        else if ($num_format=='euro')     $num_format='#,##0.00 [$€-407];[RED]-#,##0.00 [$€-407]';
        $ignore_until='';
        $escaped = '';
        for($i=0,$ix=strlen($num_format); $i<$ix; $i++)
        {
            $c = $num_format[$i];
            if ($ignore_until=='' && $c=='[')
                $ignore_until=']';
            else if ($ignore_until=='' && $c=='"')
                $ignore_until='"';
            else if ($ignore_until==$c)
                $ignore_until='';
            if ($ignore_until=='' && ($c==' ' || $c=='-'  || $c=='('  || $c==')') && ($i==0 || $num_format[$i-1]!='_'))
                $escaped.= "\\".$c;
            else
                $escaped.= $c;
        }
        return $escaped;
    }
    //------------------------------------------------------------------
    public static function add_to_list_get_index(&$haystack, $needle)
    {
        $existing_idx = array_search($needle, $haystack, $strict=true);
        if ($existing_idx===false)
        {
            $existing_idx = count($haystack);
            $haystack[] = $needle;
        }
        return $existing_idx;
    }
    //------------------------------------------------------------------
    public static function convert_date_time($date_input) //thanks to Excel::Writer::XLSX::Worksheet.pm (perl)
    {
        $days    = 0;    # Number of days since epoch
        $seconds = 0;    # Time expressed as fraction of 24h hours in seconds
        $year=$month=$day=0;
        $hour=$min  =$sec=0;

        $date_time = $date_input;
        if (preg_match("/(\d{4})\-(\d{2})\-(\d{2})/", $date_time, $matches))
        {
            list($junk,$year,$month,$day) = $matches;
        }
        if (preg_match("/(\d+):(\d{2}):(\d{2})/", $date_time, $matches))
        {
            list($junk,$hour,$min,$sec) = $matches;
            $seconds = ( $hour * 60 * 60 + $min * 60 + $sec ) / ( 24 * 60 * 60 );
        }

        //using 1900 as epoch, not 1904, ignoring 1904 special case

        # Special cases for Excel.
        if ("$year-$month-$day"=='1899-12-31')  return $seconds      ;    # Excel 1900 epoch
        if ("$year-$month-$day"=='1900-01-00')  return $seconds      ;    # Excel 1900 epoch
        if ("$year-$month-$day"=='1900-02-29')  return 60 + $seconds ;    # Excel false leapday

        # We calculate the date by calculating the number of days since the epoch
        # and adjust for the number of leap days. We calculate the number of leap
        # days by normalising the year in relation to the epoch. Thus the year 2000
        # becomes 100 for 4 and 100 year leapdays and 400 for 400 year leapdays.
        $epoch  = 1900;
        $offset = 0;
        $norm   = 300;
        $range  = $year - $epoch;

        # Set month days and check for leap year.
        $leap = (($year % 400 == 0) || (($year % 4 == 0) && ($year % 100)) ) ? 1 : 0;
        $mdays = array( 31, ($leap ? 29 : 28), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 );

        # Some boundary checks
        if($year < $epoch || $year > 9999) return 0;
        if($month < 1     || $month > 12)  return 0;
        if($day < 1       || $day > $mdays[ $month - 1 ]) return 0;

        # Accumulate the number of days since the epoch.
        $days = $day;    # Add days for current month
        $days += array_sum( array_slice($mdays, 0, $month-1 ) );    # Add days for past months
        $days += $range * 365;                      # Add days for past years
        $days += intval( ( $range ) / 4 );             # Add leapdays
        $days -= intval( ( $range + $offset ) / 100 ); # Subtract 100 year leapdays
        $days += intval( ( $range + $offset + $norm ) / 400 );  # Add 400 year leapdays
        $days -= $leap;                                      # Already counted above

        # Adjust for Excel erroneously treating 1900 as a leap year.
        if ($days > 59) { $days++;}

        return $days + $seconds;
    }
    //------------------------------------------------------------------
}